In a series of new gameplay videos released from an overseas demo of Warlords of Draenor, an interesting button appears on the upper right side of the mount window: "Summon Random Favorite Mount." The help text for the button says "Summons and dismisses a favorite mount. The mount will be chosen randomly from the favorites usable in the current area."
There's no confirmation from Blizzard that this is, or is not, legitimate, however it has been a long requested feature of the game, and seems to my eyes to be real. There are numerous addons that already do this, and Blizzard has been known to scoop up the best addon ideas out there an integrate them into the game. So this new button? Not all that surprising, but definitely appreciated.
Thanks to Chris for the tip!